Stabilized color developers



Dec. 4, 1956 J. W. BRITAIN STABILIZED COLOR DEVELO Filed Feb. 2, 1955 LOG DENSITY LO6 LOG (l/T) LOG DENSITY LOG LOG (1) PERS 1 l 1 'lvo cAReollroRA 2/05 l G./L. CARBOHYDRAZ/DE ----5 6/1.. CARBOHVDRAZ/DE '10 G./L. CARBOHYDRAZ/DE WAVELENGTH IN MILL/MICRO ---o cARaoHmRAz/M/ -'---1 G./L. CARBOHYDRAZ/DE ---s 0.4. CARBOHYDRAZ/DE -:--1a GJL. CARBOH YDRAZ/DE WAVELENGTH //v MILL m/cno/vs A 2. Sheets-Sheet 1 FIG. 1

INVENTORY .1. m emu/ 1v ATTORNEYS Dec. 4, 1956 Filed Feb. 2, 1955 GRAMS PER L/TER mm PER L/TER J. w. BRITAIN 2,772,973

STABILIZED COLOR DEVELOPERS 2 Sheets-Sheet 2 p-N-dierhylamino aniline developer+5qrams per i+er carbohydrazide;

FIG. 3'

p-Ndierhylar nino aniline developer- DAYS TRAY OFDEVELOPER WAS' PERMITTED TO STAND BEFORE SAMPLE WAS TAKEN I r I I Hydroqul'none deve|oper+5 qrolms per Iiier carbohydrazj' FIG.4

Hyd roquinone developer-.

o 2 4 6 5 I0 12 DAYS mm OF DEVELOPER ms PERMITTED 7'0 srmvo BEFORE SAMPLE ms TAKEN INVENTQR J. w. a m TA //v ATTORNEYS 2,772,973) STABILIZED coLoR DEvELoPERs J W Britain, Bingliamtdn,"l\l; Y., -assi gnor"to General Aniline '& rum CorporationfNeW York, N. Y., a corporation-of Delaware Application February 2, 1955, sriai'Noi 485,756

' Claims. (Cl. 96-55) lines, such as 4-(fl-hydroxyethylamino)-6-phenylatnino-' metanilicacid,- 4,'6 di(,B"- hydroxyethylaminol-metanilic acid and the liketsee U. S. P. 2,486,440 to Schmidt and T ulagin and U.S. P. 2,570,116 to Gunther) are employed if the dye images desired be of the azine class.

It is recognized that these color developersydue to'the presence therein of a primary amino group which is activated by another amino group in para-position'there' to, are quite susceptible to aerial oxidation: This 'fact has presented a rather serious problem with regard to the storage stability of the developers. The problem is suchthat numerous efforts have beenmade to improve the shelf life of the color developers, such as by includ-- ing components specifically designed topreserve the'developers. To this end, it has been suggested to use dextrose, hydroxylamine, p-hydroxyphenylglycine, Rongo--- While certain" of these compounds,-specifically hydroxylamine and sodium lite, sodium metaborate and the like.

metaborate, have a definite stabilizing action, fmost com pounds tested have deleterious eflecton the'development properties. This is particularly true with regard to dextrose, p-hydroxylphenylglycine, Rongolite "a'rid 'h i droxylaminer Sodium metabora-te,--whenused as e alkalfof an azine type developer, does a rather good iob it has now'been discovered," rather surprisingly that the susceptibility of color developers-to aer1al-oxi can'b e considerably minimized by the-utilizatioh "of-the reaction product of carbohydrazide with an alkali metal carbonate, on the one hand, 'ojrfan alkali" manages;-

phenyleiiediamine' and f 2,4-diarr'iii1o'aiiiline class," contain ing'suchreactioii praauetsas stabilize r s,-andthe utilizatioii offs'uch develope "-co'n titute'the pn'rpdsesaad objectsoflhe'present'inventionl v Carbohydrazid'e, Whicli has the renewing formula:

NH2:NH.CO.NH.NH2"" is a prdductavailable"oii'theopenmarket'and'bne'which 65 U. S. P. 2,419,975, T rivelli et" in any-case can be repareaacesraiag'is age732,jv01; 4 of Inorganic Syntheses. al., recommends this compound, among others, for addinited States Patent black and white developer's;Md'thisis"evideiittromllines" It W l 955s: quently shownthat'increasedstability is not a factor when 70 et seq.,columti6' of the patch the carbohydr'azide' derivatives are incorporated in developersof the phenolic type.

The quantity of stabilizer necessary 't o minirriize aerial oxidation may vary over a wide range, and, in this connection, it may be noted that I have obtained effective results with as little as 0.1 gra n per liter of developer solution and as'rn'ticaas :20 grams per' liter. The higher concentration within this range gave best protection;

It was ascertained that" when carbohydrazide is added to a color developer containiri'g' aln'alkali metalcarbonate, such as sodium carbonate, potassium carbonate or the like, the carbohydrazide reacts with the carbonateion to produce a compound, as yet unidentified, which hasthe same ability as the carbohydrazide' to act asa color developer stabilizer. Such reaction is evidenced" by' marked shift i'n the pH of the "developer solution to the alkaline side. Further experiments proved that the same or a similar reaction takes placebetween earbohydrazide and an alkali metal bicarbonate,*such as sodium bicarbonate, potassium bicarbonate and the like. 7

It will be e'vidnt'from" what has been'st'ated that when the carbohydrazide isadded'to carbonate containing developers, the aforesaid reactionproduct is the elfective stabilizer. it is equally evident that if it be desired to utilize such 'reac'tion'product as the stabilizer for developers free from carbonate, such as those in which the alkali is'providedby'sodiuriimetaborate, trisodium phosphate or the like, the reactionproduct may be preformed before adding it to the developer. aqueous solution of the carbohydrazide and carbonate;

preferably'with bicarbonate, is allowed to stand at roo'm' temperature for at "least a day prior to use. Usuallythe' reaction components 'will bepjresent in the aqueous solution in substantially equirnolar proportions or in about equal amounts.

Theicarb ohydrazide reaction products"w"ith analkali' metal carbonate or alkali metal bicarbonate are effective stabilizers for any of the previously indicated color d'e velo pers. This is true with the developers of the p-phenylenediamine class previously riientioned, or of the 2,4-

diaminoaniline class also previously illustrated,anil ea" cmplified inthe aforesaid" Schmidtan'd "Tulaginand""" Gunther patents.

The invention will be further explained by the renew veloping lightsensitive silver vel'op s fre efroiii and coiit aiiii'ng 'the aforesaid carbo= hydrazide reaction products, Figure 3 is a graph show tionto silver halide em'uljsionsi'orcftain fphotographic developers to obtain an increasedn speed and contrast of the emulsions, The developers withjwhich the patehtee is concerned, however, are of the phenolic type, i. e.,

in'gftlie"stab'ility of aco'l'o loper containingthe aforesaid*carbohydrazidereaction ptoamtsmrthg one hand,

and the same color dvel r withoiitsaid'reaetioh products, on the other hand; "and*Figur"e?4 is a graph showing the effect onstability of the carbo ydrazide reaction products"iiia liydrdc'iuifidne' dev elop'fi 2,772,973 Patented Dec. 4, 1956 To this end, an

color, formers with color de-" Part B Z-aminopyridine sulfate grams 3 Ethylenediamine tetraacetic acid do .75 Sodium sulfite do 15 Sodium carbonate (monohydrate) do 60 Sodium bromide do .86 Sodium sulfate (anhydrous) do 100 Trisodium phosphate (anhydrous) do 14 Water to make 900 cc.

Part C Carbohydrazide grams 5 Sodium carbonate (monohydrate) do 5 Sodium bicarbonate do 5 Water cc 50 (Part C solution was allowed to stand for at least one day at room temperature, i. e., about 20 C., before using.)

Parts A, B and C are mixed and the pH adjusted to 10.68 by means of trisodium phosphate or dilute sulfuric acid as the case may be.

This color developer was found to be far more stable to aerial oxidation than a similar developer from which the carbohydrazide had been omitted.

EXAMPLE II An azine color developer, particularly for reversal development, was prepared as follows:

(Part 0 solution was allowed to stand for at least one day at room temperature before using.)

Parts A, B and C are mixed and the pH adjusted to 10.68 while using trisodium phosphate or dilute sulfuric acid as the case may be.

This color developer was found to be far more stable to aerial oxidation than a similar developer from which the carbonhydrazide had been omitted.

EXAMPLE III An azine color developer was prepared as follows:

6 anilino 4 (2 hydroxyethylamino) metanilic acid g ams 5.8 2-aminopyridine sulfate do 3.1 Sodium sulfite do 20 Sodium carbonate (monohydrate) do 60 Sodium bromide do .86 Sodium sulfate do 100 Trisodium phosphate (12 parts water) do 13.5 Water to make 1 liter.

This solution was divided into four portions, to one of which was added 1 gram per liter of carbohydrazide,

4 to another 5 grams per liter, and to a third 10 grams per liter.

Each of the four solutions. (one without carbohydrazide), after standing in an open tank for six days, was used to develop an exposed light sensitive silver bromide emulsion containing a magenta color former, such as described in United States Patent 2,524,725, particularly Compound 4, column 2 thereof.

The results of such development are graphically represented in Figure l of the drawing, in which log densities are plotted as ordinates and wavelength in millimicrons as abscissa. It will be self-evident from the graphs of this figure that the aged developers containing carbohydrazide are far more effective than that free from carbohydrazide.

EXAMPLE IV Each of the four developers of Example III, after standing for six days as noted in Example III, was used to develop an exposed silver bromide emulsion containing as a color former a compound such as disclosed in United States Patent 2,500,487, and particularly that of EX- ample 3.

Figure 2 depicts the results of these tests which are again deemed to be self-explanatory.

EXAMPLE V A color developer was prepared as follows:

Calgon grams 1 Sodium bisulfite do 2 p-Diethylaminoaniline do 4 Sodium carbonate (monohydrate) do 67.5 Potassium bromide do 1 Water to make 1 liter.

This solution was divided into two portions and to one were added 2.5 grams (5 grams per liter) of carbohydrazide. The two solutions were allowed to stand in an open tray for six days and samples of each were taken each day for analysis of content of active developer ingredient.

The results of this test are illustrated by Figure 3, which establishes that the developer containing carbohydrazide is far more stable to aerial oxidation than that free from carbohydrazide.

It has been previously stated that the carbohydrazide reaction products have been found to have little effect on the stability to aerial oxidation of phenolic developers. The following test was conducted to establish the accuracy of this assertion.

A developer solution was prepared as follows:

Hot water (125 F.) cc 750 Hydroquinone grams 35 Sodium sulfite do 55 Sodium carbonate (monohydrate) do Citric aciddo 5.5 Potassium bromide do 10 Water to make 1 liter.

by the appended claims.

I claim:

l. A color developer containing as the active color developing principle a primary aromatic amino developing agent and as a stabilizer therefor against air oxidation the reaction product of carbohydrazide with a compound selected from the class consisting of alkali metal stabilizer is the reaction product of carbohydrazide and carbonates and bicarbonates. sodium carbonate.

2. The composition as defined in claim 1, wherein the 5. The composition as defined in claim 1 wherein the active developing principle is a p-phenylenediamine. stabilizer is present in an amount ranging from .1 gram 3. The composition as defined in claim 1, wherein the 5 to 20 grams per liter of the developing solution.

' active developing principle is a 2,4-diaminoaniline.

4. The composition as defined in claim 1, wherein the No reference cited. 

1. A COLOR DEVELOPER CONTAINING AS THE ACTIVE COLOR DEVELOPING PRINCIPLE A PRIMARY AROMATIC AMINO DEVELOPING AGENT AND AS A STABILIZER THEREFOR AGAINST AIR OXIDATION THE REACTION PRODUCT OF CARBOHYDRAZIDE WITH A COMPOUND SELECTED FROM THE CLASS CONSISTING OF ALKALI METAL CARBONATES AND BICARBONATES. 